Remove windows and macos from CI workflow as they are actually running linux

Removes the windows and macos matrix from the CI workflow as they were never actually setting
the OS. Both were running against the "ubuntu-latest" OS. Trying to actually use them would
not work either as neither windows or macos is supported for service containers. A different
means will be needed to test on those platforms. Until that's done, this removes those from
the matrix as we were simply running the same thing 3x for the same node versions.

Author: sehrope

Diff for: .github/workflows/ci.yml

@@ -21,7 +21,6 @@ jobs:
       - run: yarn lint
   build:
     needs: lint
-    runs-on: ubuntu-latest
     services:
       postgres:
         image: postgres:11
@@ -35,9 +34,17 @@ jobs:
         options: --health-cmd pg_isready --health-interval 10s --health-timeout 5s --health-retries 5
     strategy:
       matrix:
-        node: ['10', '12', '14', '16', '18']
-        os: [ubuntu-latest, windows-latest, macos-latest]
+        node:
+          - '10'
+          - '12'
+          - '14'
+          - '16'
+          - '18'
+          - '20'
+        os:
+          - ubuntu-latest
     name: Node.js ${{ matrix.node }} (${{ matrix.os }})
+    runs-on: ${{ matrix.os }}
     env:
         PGUSER: postgres
         PGHOST: localhost
@@ -47,6 +54,9 @@ jobs:
         SCRAM_TEST_PGUSER: scram_test
         SCRAM_TEST_PGPASSWORD: test4scram
     steps:
+      - name: Show OS
+        run: |
+          uname -a
       - run: |
           psql \
             -c "SET password_encryption = 'scram-sha-256'" \